1. Field of Invention
The present invention relates to the design and assembly of a single photovoltaic modular unit and ancillary hardware into a modular package for use under highly concentrated sunlight to convert sunlight to electricity reliably and inexpensively.
2. Prior Art
In traditional one-sun solar panels, photovoltaic devices are tightly packed or coated onto a flat substrate to capture the radiation impinging on the surface. The cells are interconnected electrically and the entire unit is encapsulated to protect it from terrestrial elements. The tightly packaged cells minimize the area not covered by the photovoltaic material, making interconnection simple and encapsulation efficient. To make photovoltaics competitive with other energy sources, the cost of the system must come down. Since the photovoltaic material can be 50% or more of the system costs, one method to reduce this cost is to minimize the amount of photovoltaic material by concentrating the solar energy to a smaller area using refractive or reflective means. This method can require individual receiver packages for each solar cell to further decrease the material costs. The smaller discrete packages however, come with concomitant disadvantages including such things as increased difficulty in interconnection, encapsulation, mechanical alignment, and thermal management requirements associated with high concentration photovoltaics.
The requirements of such packages are typically at least as stringent as those seen in one-sun applications.
1. There is the requirement of high voltage isolation from ground potential (near 2000 VDC).
2. There is the need for the protection of any active electrical parts from moisture and the elements.
3. There is the need to dissipate a higher localized heat load present on the small photovoltaic cell due to high radiation fluxes intrinsic to concentrating the sunlight.
4. There is the need for all parts of the receiving unit to withstand highly concentrated sunlight either through a prudent choice of materials or a protective element in case on any errors in tracking.
5. There is the need to accurately redirect errant rays from the primary concentrator onto the cell due to concentrator manufacturing tolerances, imaging alignment errors, or sun tracking errors.
Prior attempts to meet all of these requirements have involved either expensive materials or many different parts, with a complex and expensive assembly process. Yields and throughput have suffered as a result. Reliability problems also have resulted due in part to the high piece part count.